Co-Ordination Compounds Question 166
Question: Which of the following statements is correct with respect to the metal carbonyls of 1st transition series?
Options:
A) As $ M-C\pi $ bonding increases, the C-O bond length increases.
B) As positive charge on the central metal atom increase the C-O bond length increases.
C) As electron density on the central metal atom increase the C-O bond length increases.
D) [a] and [c] both.
Show Answer
Answer:
Correct Answer: D
Solution:
Order of C-O bond strength: $ {{[Mn{{(CO)}_6}]}^{+}}>[Cr{{(CO)}_6}]>{{[V{{(CO)}_6}]}^{-}}>{{[Ti{{(CO)}_6}]}^{2-}} $ and $ [Ni{{(CO)}_4}]>{{[Co{{(CO)}_4}]}^{-}}>{{[Fe{{(CO)}_4}]}^{2-}} $ True statement.
As +ve charge on the central metal atom increases, the less readily the metal can donate electron density into the $ {{\pi }^{*}} $ orbitals of CO ligand to weaken the C-O bond.
In the carbonylate anions, the metal has a greater electron density to be dispersed, with the result that M-C $ \pi $ bonding is enhanced and the C-O bond is diminished in strength.
